1. Field of the Invention
The invention relates to optical circuits and more particularly to optical transceivers.
2. Description of Related Art
Optical circuits offer advantages over traditional electrical circuits, particularly, in their perceived ability to provide higher speed data transmissions. Such transmissions may take place not only between computers, but also within machines, in which case board-to-board and chip-to-chip data communication using optical circuits can be utilized.
Semiconductor lasers typically come in two forms. A well known form is an “in-plane” laser, where the light inside the laser travels parallel to the substrate, such as a semiconductor substrate. More recently, a different laser geometry has developed, particularly for short distances (less than 100 meters) data communications, such as between computers. These lasers are typically known as “vertical cavity surface emitting lasers” (VCSELs). A VCSEL emits light perpendicular to the substrate as the name implies. One advantage of VCSELs are that they are capable of being modulated at high speeds with much lower electrical power than in-plane lasers. In addition, the geometry of VCSELs makes them particularly suitable for making two dimensional arrays. A third advantage is the ability to test VCSELs for fitness at the wafer level.
As noted, VCSELs emit light outward or away from a surface of the device or substrate (e.g., perpendicular to the device or substrate). One challenge to manufacturers of optical circuits such as transceivers that both transmit and receive signals and therefore may comprise VCSELs is the ability to bend or fold the light from a generally perpendicular or orthogonal transmission to a transmission lateral to the substrate and couplable to a fiber connection. At frequencies of 2.5 gigabits per second, current transceivers are able to manage such folding or bending of the light. As circuits move from 2.5 to 10 gigabits per second, the concern of managing these high frequency signals, particularly concerns of cross talk, signal delays, and signal losses, increases.
What is needed is a device for bending or folding light from a VCSELs into a fiber connection such that signal propagation may be made in a single plane.